Unsaturated aldehyde oils and method for preparing the same



United States Patent 3,112,329 UNSATURATED ALDEHYDE OILS AND METHOD FOR PREPARING THE SAME Everett H. Pryde and Donald E. Anders, Peoria, Ill., as-

signers to the United States of America as represented by the Secretary of Agriculture No Drawing. Filed Mar. 8, 1962, Ser. No. 178,512 9 Claims. (Cl. 260406) (Granted under Title 35, US. Code (1952), sec. 266) A nonexclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to improvements in the method of preparing industrially valuable monoaldehydic and polyaldehydic triglyceride products containing residual olefinic unsaturation that are formed by partially to fully ozonizing a polyunsaturated vegetable oil such as soybean, linseed, and safilower oil in a vehicle consisting of a mixture of a reactive solvent and an inert solvent and then catalytically decomposing the ozonides. The invention relates particularly to improvements in the method of catalytically hydrogenating the preferred only partially ozonized intermediates in the presence of a critical amount of pyridine to obtain improved yields of the said monoaldehydic and polyaldehydic triglycerides that for convenience we have called aldehyde oils as well as improved yields of fatty aldehydes such as caproaldehyde and pelargonaldehyde. This invention also relates to directly applicable improvements in the method of obtaining the lower alkyl esters of aliphatic aldehydes such as methyl azelaaldehydate by ozonizing methyl oleate and then catalytically reducing the ozonolysis products in methanol containing pyridine.

Still more particularly this invention relates to the preparation of improved polyfunctional aldehyde oils that are characterized by retaining unreacted original olefinic unsaturation in essentially undiminished amounts in addition to having glyceride ester functionality and aldehydric functionality. This invention also specifically relates to an unobvious improvement in the otherwise preferable but heretofore lower-yielding method of catalytically hydrogcnating the incompletely ozonized intermediate, containing olefinic unsaturation, without significant loss of said unsaturation, to this provide high yields of unsaturated aldehyde oils as well as of volatile aldehydes including caproaldehyde and pelargonaldehyde, that equal or even exceed the yields obtained therefrom by chemical reduction.

A principal object of our invention is an incompletely ozonized vegetable oil intermediate containing residual olefinic unsaturation as well as glyceride ester, peroxidic, and aldehyde functions.

Another and equally important object is an improved method of catalytically hydrogenating the above polyfunctional partially ozonized intermediate product in the presence of added pyridine to obtain improved yields of unsaturated aldehyde oils and C and C fatty aldehydes.

Other objects will become apparent in the following detailed discussion of our invention.

In accordance with the objects of the invention it appeared advisable to attempt to partially ozonize a vegetable oil such as soybean oil, safflower oil, or linseed oil (preferably to the extent of about 35 percent to about 80 percent of theory) in a nonreactive solvent containing added reactive solvent to form a highly reactive ozonide retaining significant olefinic unsaturation.

Depending on the nature of the fatty acid constituents of the starting oil and upon the extent of ozonization,

3,112,329 Patented Nov. 26, 1963 CIIiOI J (011910110 0 H0 R C|II2O R Mononldeliyde 011 H CH0 0 (C HmC IIO (EH 0 R Dialdehyde oil 1! 011,0 C (C 1191c l i 0110c (crnnono l c Trialdehyde oil wherein R is preferably a potentially reactive unsaturated acyl moiety such as olcyl, linoleyl, linolenyl, etc. or a saturated fatty acyl moiety such as myristyl, palmityl, stearyl, etc. Trialdehyde oils can be obtained only from triglycerides such as triolein having no saturated fatty acid constituent. Since unmodified vegetable oils usually contain at least a small amount of constituent saturated fatty acid, complete ozonization and reduction of such oils gives products having an average of somewhat less than three aldehyde groups per molecule. Thus, partial ozonization would give either a monoaldehyde or a dialdehyde oil.

Although it is possible to obtain good yields of unsaturated aldehyde oils and aliphatic aldehydes by chemical reduction of partially ozonized oil with zinc and acetic acid, chemical reduction is disadvantageously expensive in an industrial process, especially in view of the additional steps required for removing the zinc salts and excess acetic acid. Catalytic hydrogenation of the azionides is, therefore, preferable in an industrial process because of its lower cost and its simplicity.

However, catalytic hydrogenation over palladium on charcoal results in hydrogenation of a substantial part of the original olefinic unsaturation, increased byproduct formation, and poorer yields of the desired unsaturated aldehyde oil and fatty aldehyde products. Also, to the extent that there is a partial to a complete loss of residual unsaturation, the aldehyde oils have less functionality and are less suited as intermediates for further reactions. These poor results (runs A, D, and F) are shown in the subsequently presented tables.

In accordance with the present invention, it was discovered that, if pyridine is added to the reaction mixture during the catalytic hydrogenation phase, the above disadvantages are eliminated. Table I shows that in preparation of a monoaldehyde oil (runs A and B) or of a dialdehyde oil (runs D and E), twice as much unsaturation and one-half or less of byproduct methyl ester was formed when pyridine was present only during hydrogenation than when absent. Similarly, less than half of the byproduct ester was formed in completely ozonized soybean oil (runs F and G).

Apparently the pyridine selectively poisons the catalyst to prevent hydrogenation of the double bonds. However, it is essential that the pyridine be present only during the hydrogenation phase. If present during the ozonization step, pyridine causes undesirable side reactions to take place with a consequent decrease in alde hyde production.

TABLE I. OZONIZATION OF SOYBEAN OIL IN ETHYL ACETATE-METHANOL SOLVENT [1.538 moles unsatnration/mole fatty acid in original oil] Reaction variables Product analysis, moles/mole Ozone Pyridine present Run conduring Unsurned, satu- Alde- Methyl Total percent ration hyde ester b (est) of theory Ozoni- Hydrozation genation A 40 0. 342 0. 325 0. 057 0. 724 B 35 l). 681 0. 329 0. 029 1. 039 O 37 0. 728 0. 264 0.082 1. 074 D 77 0.140 0. 473 0.119 0. 732 E 82 0.375 0. 610 0. 0.59 1. 044 F 123 0. 612 0. 167 0. 779 G 109 0 0. 714 (1. 079 0. 793

I Ozone consumed by solvent as well as unsaturation. b Methyl ester in weight fraction from GLO analysis.

Characteristics of these oils are listed in Table II.

TABLE II.SOME CHARACTERISTICS OF ALDE- Table III shows the GLC-derived composition of the catalytically hydrogenated products after interesterification with boron trifluoride-methanol reagent.

hydrogenation is fairly critical. Although the addition of 8-10 percent of pyridine based on the weight of the solution is optimal, less than 5 percent thereof results in the loss of most of the unsaturation whereas with additions exceeding 15 percent of the solution, pyridine oxide formation becomes a strongly competitive reaction and product purity is distinctly lowered.

With the exception of Example 1 which is presented for purposes of comparison, the following examples are given to provide a more complete understanding of the invention and not to limit the scope thereof.

Example I CONVENTIONAL CATALYTIC REDUCTION PYRIDINE) (RUN A OF TABLES Soybean oil (40.0 g., 0.207 mole of unsaturation) was dissolved in 200 ml. of ethyl acetate and ml. of absolute methanol. Oxygen containing 1.01 mrnoles of ozone/liter of oxygen was passed through the solution (chilled to 12 C.) at a rate of about 2.06 l./min. for 40 min. The amount of unreacted ozone passing through and out of the reactor was less than 0.3 percent of theory, while the amount absorbed by the reaction mixture was 39.7 percent of theory. After ozonization, solution and reaction flask were flushed with nitrogen, and 0.1 g. 10 percent palladium on charcoal was added. Hydrogenation was carried out at room temperature and atmospheric pressure for 330 min, during whcih time the catalyst became slowly coated with stearins that eventually prevented completion of the hydrogenation. The reaction mixture was warmed to 40 C. to release the catalyst, and hydrogenation continued for another 180 min. until the peroxide test was negative. The solution was filtered, 200 ml. of CH Cl were added to the filtrate, and filtrate was then washed three times with water to remove any malonaldehyde. Each aqueous extraction was backwashed with a small amount of 011 01 The solution was dried, filtered, and distilled in vacuo, under nitrogen. The yield of unsaturated aldehyde oil was 34.55 g. with a carbonyl conversion of 35.1 percent (equivalent to 0.976 aldehyde group/molecule or 0.325 mole/mole).

)(W'ITIIOUT Example 2 REDUCTION \VITH PYRIDINE (RUN 13 OF TABLES) Soybean oil (40.0 g., 0.207 g. mole of unsaturation) was dissolved in 200 ml. of ethyl acetate and 50 ml. of

TABLE III.GAS LIQUID CHROMATOGRAPHY OF ALDEHYDE OILS [As methyl esters] Com position, Area Percent Run Methyl Dimethyl Methyl Methyl Methyl Methyl Methyl Unazelaalazelate palmltate stearate oleate linoleato linolenate known dehydate Original o 1 10. 9 s. 4 211.0 53. o 6.2 A 21.1 5. 7 15.1 21.0 34. 4 1. 5 0.6 0. 5 1 15. l 2. 9 18.5 3.0 25.4 33.1 0.6 1. 4 C 18.0 8. 7 10 5 2. 2 20. 0 30. 0 1. 4 2. 6 D 36. 9 12. 5 16. 7 10.8 10. 8 2.1 0 10. 2 E 49.9 5.9 18.8 5.4 11.7 6.7 0 F 59. s 16. s 17.1 5.2 0 0 0 1.1 G 69.1 7. 9 16. s 5. 4 0 0 0 8 1 Original soybean oil before ozonization.

Our novel aldehyde oils are highly reactive to urea, polyols, and phenolic compounds and therewith give soft, flexible, infusib-le, insoluble gels, indicating a high degree of crosslinking. The presence in our unsaturated aldehyde oils of three distinct types of functionality, namely: aldehydic, ole-finic, and glyceride ester, makes them particularly useful as modifying agents for synthetic resins. The fatty aldehydes have industrial significance as intermediates for the preparation of polyamide resins.

In experiments with methyl oleate, and with polyunsaturated vegetable oils, we have further found that the proportion of pyridine in the solvent used for the catalytic absolute methanol. Oxygen containing 0.834 moles of ozone/liter of oxygen was passed through the solution (chilled to 12 C.) at the rate of approximately 2.21 l./rnin. for 40 minutes. The amount of ozone passing through the reactor was less than 0.2 percent of theory, while the amount absorbed by the reaction mixture was 35.4 percent of theory. The solution and reaction flask were flushed with nitrogen, and 26.0 g. of pyridine (10.6 percent by weight of solvent) and 0.1 g. 10 percent palladium on charcoal catalyst were added. Hydrogen was *bubbled through the solution at room temperature and atmospheric pressure for minutes until the peroxide test was negative. The solution was filtered, and 200 ml. methylene chlorine were added to the filtrate which was there washed with dilute hydrochloric acid and finally with water until neutral. Each water wash was backwashed with a small amount of CH CI The aldehyde oil was isolated by removal of the volatile aldehydes (principally caproaldehyde and pelargonaldehyde) in vacuo under nitrogen. The yield of unsaturated aldehyde oil was 34.78 g. with a carbonyl conversion in the aldehyde oil of 39.5 percent (equivalent to 0.991 aldehyde group/molecule or 0.329 mole/mole). Unreacted olefinic unsaturation in the aldehyde oil was 0.681 mole/ mole.

Example 3 INTERESTERIFIUATION F ALDEHYDE 01L WITH BFal\leOH REAGENT Two grams of the aldehyde oil of Example 2 were refiuxed in the presence of 10 ml. of 10 percent boron trifiuon'de in methanol for one hour. The solution was cooled and neutralized with a dilute sodium bicarbonate solution to methyl organge end point. The mixture was then extracted three times with a small amount of CH Cl and the methylene chloride fractions were combined and washed with Water until neutral. Two washes were required. The solution was dried, filtered, and evaporated under nitrogen on a steam bath to remove any solvent. Analyses were run on the residues, which consisted of methyl esters of the fatty acids, the dimethyl acetal of methyl azelaaldehydate, and dimethyl azelate.

Example 4 REDUCTION WITH PYRIDINE (RUN E OF TABLES) Soybean oil (40.0 g., 0.207 g. mole of unsaturation) was dissolved in 200 ml. of ethyl acetate and 50ml. of absolute methanol. Oxygen containing 1.008 mmoles of ozone/ liter of oxygen was passed through the solution (chilled to 10 C.), at the rate of approximately 2.10 l./rnin. for 80 minutes. The amount of ozone passing through the reactor was approximately 0.4 percent of theory, while the amount absorbed by the reaction mixture was 82.0 percent of theory. The solution and reaction flask were flushed with nitrogen, and 26.0 g. of pyridine (10 percent by wt. of soln.) and 0.1 g. 10 percent palladium. on charcoal catalyst were added. Hydrogen was bubbled through the solution at room temperature and atmospheric pressure for 240 minutes until the peroxide test was negative. The solution was filtered and the aldehydic materials isolated as before. The yield of unsaturated aldehyde oil was 30.85 g. with a carbonyl conversion in the aldehyde oil of 70.0 percent (equivalent to 1.83 aldehyde groups/ molecule or 0.610 mole/mole). Unreacted olefinic unsaturation in the aldehyde oil was 0.375 mole/mole.

Example 5 OZONIZATION AND REDUCTION OF METHYL ULEATE IN IvllCTlIANOL-IYRIUINE Methyl oleate (20.08 g., 0.07 mole of unsaturation) was dissolved in a solution of 250 ml. absolute methanol and 22.8 g. (0.28 g. mole) of pyridine. Oxygen containing 0.966 mmoles of ozone per liter of oxygen was passed through the solution at the rate of approximately 2.41 l./mm., for 36 min., at room temperature. The amount of unreacted ozone was 1.2 mmoles, amounting to 1.8 percent of the absorption theoretically expected, while the amount of ozone absorbed Was 118 percent of theory. The ozonolysis solution and the reactor flask were flushed with nitrogen, and 0.1 g. percent palladium on charcoal catalyst was added. Hydrogenation was carried out for 100 minutes at room temperature and atmospheric pressure. The solution was filtered and the methanol removed by distillation on a steam bath under a slight vacuum. The temperature was kept as low as possible during distillation to reduce the possibility of aldol condensation because of the presence of the basic compound pyridine. The residue was distilled under reduced pressures through a 1 inch x 6 inch glass helices-packed column, and two main aldehydic fractions were collected. The pelargonaldehyde fraction (7.34 g, 74 percent) boiling 94-96" (22 mm.), 11 1.4189, had a chemical purity (by hydroxylamine hydrochloride method) of 82 percent. The methyl azelaaldehydate fraction (10.22 g., 76 percent) boiling 97- 100 (0.34 mm.), r1 1.4346, had a chemical purity 88.3 percent and a GLC purity of 88.7 percent.

This example illustrates the fact that, in the ozonization and reduction of methyl oleate, it is possible to add the pyridine to the solvent initially in the ozonization step.

We claim:

1. A method of obtaining improved yields of nonvolatile aldehydic glyoeride ester-type oils containing residual olefinic unsaturation and selected from the group consisting of monoaldehyde oils and di-aldehyde oils conforming respectively to Formula A and Formula 13 ll 01-1200 (011910110 orron CHgOR (A) 0 ll CHgOC (011916 HO CIIO (3 (C H010 H0 wherein R represents an unsaturated acyl radical selected from the group consisting of oleyl, linoleyl, and linolenyl, comprising the steps of ozonizing a polyunsaturated vegetable oil to the extent of about 37 percent to about 77 percent of theory in a chilled solvent mixture consisting of 80 percent ethyl acetate and 20 percent methanol, flushing the system with nitrogen, adding about 8-12 percent of pyridine based on the weight of said solvent mixture, introducing hydrogen. thereto at room temperature in the presence of palladium catalyst until the peroxide test becomes negative, filtering off the catalyst, neutralizing the filtrate, and evaporating off the volatile aldehyde byproducts in vacuo.

2. The method of claim 1 wherein soybean oil is ozonized to the extent of 35 percent, to produce a nonvolatile monoaldehydic ester-type oil containing 0.681 mole of unreacted olefinic unsaturation and 0.329 mole of aldehyde per mole.

3. The method of claim 1 wherein soybean oil is ozonized to the extent of 82 percent, to produce a nonvolatile, dialdehydic ester-type oil containing 0.375 mole of unreacted olefinic unsaturation and 0.610 mole of aldehyde per mole.

4. A method of obtaining a nonvolatile trialdehyde oil corresponding to the formula:

CH1O(%(CII2)TCHO l 0 OHOK i (CHdzCHO 0 GU26) (C HzhClIO comprising the steps of fully ozonizing triolein in a solvent mixture consisting of 80 percent ethyl acetate and 20 percent methanol, adding to the ozonized reaction mixture about 8-12 percent of pyridine based on the weight of said solvent mixture, introducing hydrogen thereto at room temperature in the presence of palladium catalyst until the peroxide test becomes negative, removing the catalyst, neutralizing the remaining reaction mixture, and evaporating volatile aldehyde byproducts in vacuo.

5. The nonvolatile trialdehyde oil having the formula:

I! CHzOC (CHzlYCHO ii CHOC (CH2)7CIIO II cmoowmhcuo 6. A nonvolatile aldehydic glyceride oil having the formula:

II CHzO C (O H:|)1CHO CHOR CIIQOR wherein R represents an unsaturated acyl radical selected from the group consisting of oleyl, linoleyl, and linolenyl.

7. A nonvolatile aldehydic glyceride oil having the formula:

ll OHIO (CH2)1CIIO II CHOC(CH l CHO OH:R

wherein R represents an unsaturated acyl radical selected from the group consisting of oleyl, linoleyl, and linolenyl.

8. A method of preparing methyl azelaaldehydate comprising fully ozonizing methyl oleate dissolved in a solvent mixture consisting of about 11 parts by volume of absolute methanol and 1 part by volume of pyridine, hydrogenating the ozonization products at room temperature H cmoowmhcuo CIIOR CIIIOR CHO KHhhCIIO CIHOR and O C 2 II:)1GHO I 0 CH0% (CH2)1CHO I 0 CIIO("](CH2).'CIIO wherein R represents an unsaturated acyl radical selected from the group consisting of oleyl, linoleyl, and linolenyl.

No references cited. 

1. A METHOD OF OBTAINING IMPROVED YIELDS OF NONVOLATILE ALDEHYDIC GLYCERIDE ESTER-TYPE OILS CONTAINING RESIDUAL OLEFINIC UNSATURATION AND SELECTED FROM THE GROUP CONSISTING OF MONO-ALDEHYDE OILS AND DI-ALDEHYDE OILS CONFORMING RESPECTIVELY TO FORMULA A AND FORMULA B
 9. A NON-VOLATILE ALDEHYDE OIL SELECTED FROM THE GROUP HAVING THE FORMULA: 